Viologens-based redox mediators with tunable HOMO–LUMO energy gap for highly effective hydrogen peroxide electrosynthesis  

作　　者：Yang Gao Xiaohui Xu Yue Niu Xinran Hu Zeyu Li Longkun Yang Linjie Zhi Bin Wang 

机构地区：[1]CAS Key Laboratory of Nanosystem and Hierarchical Fabrication,CAS Center for Excellence in Nanoscience,National Center for Nanoscience and Technology,Beijing 100190,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]The Beijing Key Laboratory for Nano-Photonics and Nano-Structure(NPNS),Department of Physics,Capital Normal University,Beijing 100048,China [4]College of New Energy,China University of Petroleum(East China),Qingdao 266580,China

出　　处：《Nano Research》2023年第12期12936-12941,共6页纳米研究（英文版）

基　　金：financial support from the National Key R&D Program of China(Nos.2021YFA1202802,2022YFF0712200,and 2022YFE0127400);the National Natural Science Foundation of China(Nos.U20A20131 and 51425302);the China Postdoctoral Science Foundation Funded Project(No.2021M690801);the CAS Pioneer Hundred Talents Program.

摘　　要：In comparison with the developing nano-carbon catalysts,some small organic molecules are also emerging as catalysts with typical features,however,their working mechanism is still unclear.Here,we synthesized a series of viologen-based heterogeneous catalysts with the same molecular skeleton but different substituent groups through anion exchange engineering.These viologen-based molecules were used as a model catalyst to investigate the underlying structure–function relationship for small molecules-based H_(2)O_(2) electrosynthesis.Differing from the commonly reported carbon-based electrocatalysts,viologens can produce H_(2)O_(2) in a synergistic manner,which means that viologens can not only directly catalyze oxygen reduction but also serve as a redox mediator.We found that the ring current and H_(2)O_(2) selectivity of viologens deliver an increasing trend with the increase of the alkyl chain length of alkyl-substituted viologens and further increase when using benzyl as the substituent group.As a result,a benzyl-substituted viologen(BV)delivers the best electrocatalytic performance among the samples,including the highest H_(2)O_(2) selectivity of 96.9%at 0.6 V and the largest ring current density of about 13.6 mA·mmol-1.Furthermore,density functional theory(DFT)calculations disclose that the carbon atoms bonded with positively charged N are the active sites and the small highest occupied molecular orbital(HOMO)–lowest unoccupied molecular orbital(LUMO)energy gap of BV is beneficial to the synergistic mechanism for H_(2)O_(2) production.This work sheds new insight into the efficient H_(2)O_(2) production in a synergistic manner for small molecules-based electrocatalysts.

关 键 词：VIOLOGENS electrocatalysis hydrogen peroxide redox mediator oxygen reduction 

分 类 号：O62[理学—有机化学]